The present invention relates to oral compositions containing a zinc compound capable of furnishing zinc ions in the oral cavity, and an antibacterial agent, for use in the mouth to retard the accumulation of dental plaque and/or calculus.
Dental plaque forms as a film on teeth. It is a product of microbial growth, a dense microbial layer consisting of a mass of microorganisms embedded in a matrix, which accumulates on the tooth surfaces. The microorganisms are mainly coccoidal organisms, particularly in early plaque, which, in the mouths of some persons at least, change to filamentous organisms after a few days.
A wide variety of microorganisms are found in the oral cavity, among these being gram-positive anaerobic rods presumably comprising Corynebacterium, Actinomyces, and Propionibacterium, Neisseria, Nocardia, Fusobacterium, Veillonella, and Streptococci, such as S. mutens, S. bovis, S. salivarius, and gram-positive streptococci of the genus Peptostreptococcus (See Robert J. Fitzgerald in "The Alabama Journal of Medical Sciences" Volume 5, No. 3, July, 1968, pp. 241-242).
Bacteria associated with dental plaque and the development of calculus include Streptococci, Corynebacterium, and filamentous Nocardia-like organisms. These are gram-positive organisms.
In addition to the aforementioned microorganisms, there are present in plaque relatively small amounts of other substances such as salivary proteins, carbohydrates, epithelial cells, and leucocytes.
Dental plaque has been observed to form following a dental prophylaxis, due to bacteria which grew out of defects in the tooth enamel where they had resided and remained unaffected by the prophylaxis treatment.
Plaque may form on any part of the tooth surface, and is found particularly at the gingival margin, in cracks in the enamel, and on the surface of dental calculus.
The importance of giving consideration to the action of plaque on the teeth lies in the tendency of plaque to produce gingivitis and perhaps other types of periodontal disease, as well as dental caries and dental calculus.
Dental plaque is a precursor of dental calculus. The latter forms from the plaque that accumulates on the teeth in the form of a hard mineralized deposit. It is particularly prone to form at the gingival margin, i.e., the junction of the tooth and gingiva. Both the bacterial and non-bacterial components of plaque are mineralized to form calculus, which comprises, in addition to mineralized bacteria, organic constituents, such as epithelial cells, live bacteria, salivary proteins, leucocytes, and crystals of substances having molecularly bound calcium and phosphorus, e.g., hydroxyapatite, 3[Ca.sub.3 (PO.sub.4).sub.2 ].sup.. Ca(OH).sub.2, octacalcium phosphate, Ca.sub.8 (HPO.sub.4).sub.2 (PO.sub.4).sub.4 .multidot.5H.sub.2 O, brushite, CaHPO.sub.4 .multidot.2H.sub.2 O, and whitlockite, which is considered to have the formula beta-Ca.sub.3 (PO.sub.4).sub.2.
Calculus, like plaque, is considered to be a prime causative factor in periodontal disease.
Regular tooth brushing with a conventional dentifrice may, for some persons, greatly retard or even prevent the accumulation of calculus. For other persons however calculus builds up rapidly even with regular brushing. Removal by a dentist is currently the only safeguard against serious gingival inflammation which can be caused by dental calculus.